Effect of wing deformation by camber angle on aerodynamic performance of flapping micro air vehicles

This study investigates unsteady aerodynamic characteristics of the three-dimensional flexible cambered wings of a flapping-wing micro air vehicle in hover. A fluid–structure interaction solver to simulate large-deformation wings is developed for a realistic modeling of wing structure and geometry. Validation against experimental data for an anisotropic Zimmerman wing is accomplished. In addition, cross-validation is conducted against the experimental results obtained also in the present paper to establish more accurate analysis for flat and cambered wings. Investigation on the unsteady vortex structures around those wings including passive twisting deformation is carried out. Then, a parametric study is conducted to evaluate the aerodynamic performance with respect to the camber angle. By this, the angles producing the largest thrust and efficiency are estimated and their effects are analyzed in terms of the stroke phase. The wing with the smallest camber angle where the vortex pairing phenomenon occurs significantly is found to be advantageous at the beginning of the stroke. However, the largest thrust and efficiency are obtained for a cambered wing at a different angle due to the vortex attachment and the net force vector formation. As a result, it is found that the camber angle will be an important parameter that is potentially capable of improving the aerodynamic performance of the flapping-wing micro air vehicles.